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<div class="refentry">
<a name="gst-plugins-good-plugins-rtpulpfecenc"></a><div class="titlepage"></div>
<div class="refnamediv"><table width="100%"><tr>
<td valign="top">
<h2><span class="refentrytitle"><a name="gst-plugins-good-plugins-rtpulpfecenc.top_of_page"></a>rtpulpfecenc</span></h2>
<p>rtpulpfecenc — Generic RTP Forward Error Correction (FEC) encoder</p>
</td>
<td class="gallery_image" valign="top" align="right"></td>
</tr></table></div>
<div class="refsect1">
<a name="gst-plugins-good-plugins-rtpulpfecenc.properties"></a><h2>Properties</h2>
<div class="informaltable"><table class="informaltable" border="0">
<colgroup>
<col width="150px" class="properties_type">
<col width="300px" class="properties_name">
<col width="200px" class="properties_flags">
</colgroup>
<tbody>
<tr>
<td class="property_type"><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a></td>
<td class="property_name"><a class="link" href="gst-plugins-good-plugins-rtpulpfecenc.html#GstRtpUlpFecEnc--multipacket" title="The “multipacket” property">multipacket</a></td>
<td class="property_flags">Read / Write / Construct</td>
</tr>
<tr>
<td class="property_type"><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a></td>
<td class="property_name"><a class="link" href="gst-plugins-good-plugins-rtpulpfecenc.html#GstRtpUlpFecEnc--mux-seq" title="The “mux-seq” property">mux-seq</a></td>
<td class="property_flags">Read / Write / Construct</td>
</tr>
<tr>
<td class="property_type"><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#guint"><span class="type">guint</span></a></td>
<td class="property_name"><a class="link" href="gst-plugins-good-plugins-rtpulpfecenc.html#GstRtpUlpFecEnc--percentage" title="The “percentage” property">percentage</a></td>
<td class="property_flags">Read / Write / Construct</td>
</tr>
<tr>
<td class="property_type"><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#guint"><span class="type">guint</span></a></td>
<td class="property_name"><a class="link" href="gst-plugins-good-plugins-rtpulpfecenc.html#GstRtpUlpFecEnc--percentage-important" title="The “percentage-important” property">percentage-important</a></td>
<td class="property_flags">Read / Write / Construct</td>
</tr>
<tr>
<td class="property_type"><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#guint"><span class="type">guint</span></a></td>
<td class="property_name"><a class="link" href="gst-plugins-good-plugins-rtpulpfecenc.html#GstRtpUlpFecEnc--protected" title="The “protected” property">protected</a></td>
<td class="property_flags">Read</td>
</tr>
<tr>
<td class="property_type"><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#guint"><span class="type">guint</span></a></td>
<td class="property_name"><a class="link" href="gst-plugins-good-plugins-rtpulpfecenc.html#GstRtpUlpFecEnc--pt" title="The “pt” property">pt</a></td>
<td class="property_flags">Read / Write / Construct</td>
</tr>
<tr>
<td class="property_type"><a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#guint"><span class="type">guint</span></a></td>
<td class="property_name"><a class="link" href="gst-plugins-good-plugins-rtpulpfecenc.html#GstRtpUlpFecEnc--ssrc" title="The “ssrc” property">ssrc</a></td>
<td class="property_flags">Read / Write / Construct</td>
</tr>
</tbody>
</table></div>
</div>
<a name="GstRtpUlpFecEnc"></a><div class="refsect1">
<a name="gst-plugins-good-plugins-rtpulpfecenc.other"></a><h2>Types and Values</h2>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="name">
<col class="description">
</colgroup>
<tbody><tr>
<td class="datatype_keyword">struct</td>
<td class="function_name"><a class="link" href="gst-plugins-good-plugins-rtpulpfecenc.html#GstRtpUlpFecEnc-struct" title="struct GstRtpUlpFecEnc">GstRtpUlpFecEnc</a></td>
</tr></tbody>
</table></div>
</div>
<div class="refsect1">
<a name="gst-plugins-good-plugins-rtpulpfecenc.object-hierarchy"></a><h2>Object Hierarchy</h2>
<pre class="screen"> <a href="/usr/share/gtk-doc/html/gobject/gobject-The-Base-Object-Type.html#GObject-struct">GObject</a>
<span class="lineart">╰──</span> <a href="/usr/share/gtk-doc/html/gobject/gobject-The-Base-Object-Type.html#GInitiallyUnowned">GInitiallyUnowned</a>
<span class="lineart">╰──</span> <a href="/usr/share/gtk-doc/html/gstreamer-1.0/GstObject.html#GstObject-struct">GstObject</a>
<span class="lineart">╰──</span> <a href="/usr/share/gtk-doc/html/gstreamer-1.0/GstElement.html#GstElement-struct">GstElement</a>
<span class="lineart">╰──</span> GstRtpUlpFecEnc
</pre>
</div>
<div class="refsect1">
<a name="gst-plugins-good-plugins-rtpulpfecenc.description"></a><h2>Description</h2>
<p>Generic Forward Error Correction (FEC) encoder using Uneven Level
Protection (ULP) as described in RFC 5109.</p>
<p>It differs from the RFC in one important way, it multiplexes the
FEC packets in the same sequence number as media packets. This is to be
compatible with libwebrtc as using in Google Chrome and with Microsoft
Lync / Skype for Business.</p>
<p>Be warned that after using this element, it is no longer possible to know if
there is a gap in the media stream based on the sequence numbers as the FEC
packets become interleaved with the media packets.</p>
<p>This element will insert protection packets in any RTP stream, which
can then be used on the receiving side to recover lost packets.</p>
<p>This element rewrites packets' seqnums, which means that when combined
with retransmission elements such as <a class="link" href="gst-plugins-good-plugins-rtprtxsend.html#GstRtpRtxSend"><span class="type">GstRtpRtxSend</span></a>, it *must* be
placed upstream of those, otherwise retransmission requests will request
incorrect seqnums.</p>
<p>A payload type for the protection packets *must* be specified, different
from the payload type of the protected packets, with the GstRtpUlpFecEnc:pt
property.</p>
<p>The marker bit of RTP packets is used to determine sets of packets to
protect as a unit, in order to modulate the level of protection, this
behaviour can be disabled with GstRtpUlpFecEnc:multipacket, but should
be left enabled for video streams.</p>
<p>The level of protection can be configured with two properties,
<a class="link" href="gst-plugins-good-plugins-rtpulpfecenc.html#GstRtpUlpFecEnc--percentage" title="The “percentage” property"><span class="type">“percentage”</span></a> and <a class="link" href="gst-plugins-good-plugins-rtpulpfecenc.html#GstRtpUlpFecEnc--percentage-important" title="The “percentage-important” property"><span class="type">“percentage-important”</span></a>,
the element will determine which percentage to use for a given set of
packets based on the presence of the <a href="/usr/share/gtk-doc/html/gstreamer-1.0/GstBuffer.html#GST-BUFFER-FLAG-NON-DROPPABLE:CAPS"><span class="type">GST_BUFFER_FLAG_NON_DROPPABLE</span></a>
flag, upstream payloaders are expected to set this flag on "important"
packets such as those making up a keyframe.</p>
<p>The percentage is expressed not in terms of bytes, but in terms of
packets, this for implementation convenience. The drawback with this
approach is that when using a percentage different from 100 %, and a
low bitrate, entire frames may be contained in a single packet, leading
to some packets not being protected, thus lowering the overall recovery
rate on the receiving side.</p>
<p>When using <a class="link" href="gst-plugins-good-plugins-rtpbin.html#GstRtpBin"><span class="type">GstRtpBin</span></a>, this element should be inserted through the
<a class="link" href="gst-plugins-good-plugins-rtpbin.html#GstRtpBin-request-fec-encoder" title="The “request-fec-encoder” signal"><span class="type">“request-fec-encoder”</span></a> signal.</p>
<div class="refsect2">
<a name="id-1.2.228.7.12"></a><h3>Example pipeline</h3>
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1</pre></td>
<td class="listing_code"><pre class="programlisting">gst<span class="gtkdoc opt">-</span>launch<span class="gtkdoc opt">-</span><span class="number">1.0</span> videotestsrc <span class="gtkdoc opt">!</span> x264enc <span class="gtkdoc opt">!</span> video<span class="gtkdoc opt">/</span>x<span class="gtkdoc opt">-</span>h264<span class="gtkdoc opt">,</span> profile<span class="gtkdoc opt">=</span>baseline <span class="gtkdoc opt">!</span> rtph264pay pt<span class="gtkdoc opt">=</span><span class="number">96</span> <span class="gtkdoc opt">!</span> rtpulpfecenc percentage<span class="gtkdoc opt">=</span><span class="number">100</span> pt<span class="gtkdoc opt">=</span><span class="number">122</span> <span class="gtkdoc opt">!</span> udpsink port<span class="gtkdoc opt">=</span><span class="number">8888</span></pre></td>
</tr>
</tbody>
</table>
</div>
This example will receive a stream with FEC and try to reconstruct the packets.
Example programs are available at
<a class="ulink" href="https://gitlab.freedesktop.org/gstreamer/gstreamer-rs/blob/master/examples/src/bin/rtpfecserver.rs" target="_top">rtpfecserver.rs</a>
and
<a class="ulink" href="https://gitlab.freedesktop.org/gstreamer/gstreamer-rs/blob/master/examples/src/bin/rtpfecclient.rs" target="_top">rtpfecclient.rs</a>
</div>
<p>See also: <a class="link" href="gst-plugins-good-plugins-rtpulpfecdec.html#GstRtpUlpFecDec"><span class="type">GstRtpUlpFecDec</span></a>, <a class="link" href="gst-plugins-good-plugins-rtpbin.html#GstRtpBin"><span class="type">GstRtpBin</span></a></p>
<div class="refsynopsisdiv">
<h2>Synopsis</h2>
<div class="refsect2">
<a name="id-1.2.228.7.14.1"></a><h3>Element Information</h3>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term">plugin</span></p></td>
<td>
<a class="link" href="gst-plugins-good-plugins-plugin-rtp.html#plugin-rtp">rtp</a>
</td>
</tr>
<tr>
<td><p><span class="term">author</span></p></td>
<td>Mikhail Fludkov <misha@pexip.com></td>
</tr>
<tr>
<td><p><span class="term">class</span></p></td>
<td>Codec/Payloader/Network/RTP</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2">
<a name="id-1.2.228.7.14.2"></a><h3>Element Pads</h3>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term">name</span></p></td>
<td>sink</td>
</tr>
<tr>
<td><p><span class="term">direction</span></p></td>
<td>sink</td>
</tr>
<tr>
<td><p><span class="term">presence</span></p></td>
<td>always</td>
</tr>
<tr>
<td><p><span class="term">details</span></p></td>
<td>application/x-rtp</td>
</tr>
</tbody>
</table></div>
<div class="variablelist"><table border="0" class="variablelist">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term">name</span></p></td>
<td>src</td>
</tr>
<tr>
<td><p><span class="term">direction</span></p></td>
<td>source</td>
</tr>
<tr>
<td><p><span class="term">presence</span></p></td>
<td>always</td>
</tr>
<tr>
<td><p><span class="term">details</span></p></td>
<td>application/x-rtp</td>
</tr>
</tbody>
</table></div>
</div>
</div>
</div>
<div class="refsect1">
<a name="gst-plugins-good-plugins-rtpulpfecenc.functions_details"></a><h2>Functions</h2>
<p></p>
</div>
<div class="refsect1">
<a name="gst-plugins-good-plugins-rtpulpfecenc.other_details"></a><h2>Types and Values</h2>
<div class="refsect2">
<a name="GstRtpUlpFecEnc-struct"></a><h3>struct GstRtpUlpFecEnc</h3>
<pre class="programlisting">struct GstRtpUlpFecEnc;</pre>
</div>
</div>
<div class="refsect1">
<a name="gst-plugins-good-plugins-rtpulpfecenc.property-details"></a><h2>Property Details</h2>
<div class="refsect2">
<a name="GstRtpUlpFecEnc--multipacket"></a><h3>The <code class="literal">“multipacket”</code> property</h3>
<pre class="programlisting"> “multipacket” <a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a></pre>
<p>Apply FEC on multiple packets.</p>
<p>Flags: Read / Write / Construct</p>
<p>Default value: TRUE</p>
</div>
<hr>
<div class="refsect2">
<a name="GstRtpUlpFecEnc--mux-seq"></a><h3>The <code class="literal">“mux-seq”</code> property</h3>
<pre class="programlisting"> “mux-seq” <a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a></pre>
<p>Mux seqnum for media and fec packets in same seqnum space.</p>
<p>Flags: Read / Write / Construct</p>
<p>Default value: FALSE</p>
</div>
<hr>
<div class="refsect2">
<a name="GstRtpUlpFecEnc--percentage"></a><h3>The <code class="literal">“percentage”</code> property</h3>
<pre class="programlisting"> “percentage” <a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#guint"><span class="type">guint</span></a></pre>
<p>FEC overhead percentage for the whole stream.</p>
<p>Flags: Read / Write / Construct</p>
<p>Allowed values: <= 100</p>
<p>Default value: 0</p>
</div>
<hr>
<div class="refsect2">
<a name="GstRtpUlpFecEnc--percentage-important"></a><h3>The <code class="literal">“percentage-important”</code> property</h3>
<pre class="programlisting"> “percentage-important” <a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#guint"><span class="type">guint</span></a></pre>
<p>FEC overhead percentage for important packets.</p>
<p>Flags: Read / Write / Construct</p>
<p>Allowed values: <= 100</p>
<p>Default value: 0</p>
</div>
<hr>
<div class="refsect2">
<a name="GstRtpUlpFecEnc--protected"></a><h3>The <code class="literal">“protected”</code> property</h3>
<pre class="programlisting"> “protected” <a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#guint"><span class="type">guint</span></a></pre>
<p>Count of protected packets.</p>
<p>Flags: Read</p>
<p>Default value: 0</p>
</div>
<hr>
<div class="refsect2">
<a name="GstRtpUlpFecEnc--pt"></a><h3>The <code class="literal">“pt”</code> property</h3>
<pre class="programlisting"> “pt” <a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#guint"><span class="type">guint</span></a></pre>
<p>The payload type of FEC packets.</p>
<p>Flags: Read / Write / Construct</p>
<p>Allowed values: <= 255</p>
<p>Default value: 255</p>
</div>
<hr>
<div class="refsect2">
<a name="GstRtpUlpFecEnc--ssrc"></a><h3>The <code class="literal">“ssrc”</code> property</h3>
<pre class="programlisting"> “ssrc” <a href="/usr/share/gtk-doc/html/glib/glib-Basic-Types.html#guint"><span class="type">guint</span></a></pre>
<p>The SSRC to use on FEC'd packets.</p>
<p>Flags: Read / Write / Construct</p>
<p>Default value: 0</p>
</div>
</div>
</div>
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